The department's Public Drinking Water Branch is responsible for ensuring Missouri's public water systems follow state and federal rules and regulations and provide safe drinking water to all Missouri citizens and visitors. Individual water systems are required to submit water samples for laboratory testing to verify the water they are serving to the public meets all federal and state standards. How often and where samples are taken varies by system and contaminant.

Certified Laboratories

A certified laboratory must be used for any testing required by the department's Public Drinking Water Branch. Lists for both certified chemical and microbiological laboratories are provided below. Analysis of water samples from private residences or private wells does not have to be done by a certified laboratory. There are other laboratories capable of performing analyses of private water samples in addition to the laboratories. These other labs have chosen not to go through our certification process, but may produce equivalent results if they have adequate quality assurance or quality control in place.

Consumer Confidence Reports

Consumer Confidence Reports are updated annually by April 1. Information and instructions for community water supplies can be found at the following links along with the required certification form that must be submitted to the department by Oct. 1 each year.

Request Additional Sampling Bottles

Sealed, sterile bottle used to collect bacteriological samples of drinking water samples

An online form can be used in place of the enclosed postcard that comes with the sample bottles. These bottles are sent via UPS to the Sampler, or SA, that we have listed in our database. If you need to verify the contact information we have is current (change of personnel, address, telephone number, etc.), use the link Drinking Water Watch to check our data. If you do need your contact information updated, check yes for Contact Changes and enter the correct data. If you have questions, call the  Public Drinking Water Branch at 573-526-3832.

Bacteriological Sampling

Individual water systems are required to submit samples of their water for laboratory testing to verify the water they are serving to the public meets all federal and state standards. Please contact the department's Regional Office that assists your county, to discuss the sampling procedures, sample siting plan (routine and repeat sites) and sample collection schedule (planned rotation of sample sites throughout the year or season of operation) revisions, and assessments.

Sampling Schedule

How often and where samples are taken varies by system and contaminant and is detailed in the department's Bacteriological Sampling Calendars. Systems using independent laboratories are responsible for ensuring the sample results are submitted to the department by the 10th of the following month.

Sampling Procedures

If your system is using an independent state certified laboratory for bacteriological analysis, you must use bottles and sample forms provided by the independent laboratory and follow their shipping procedures. The following sampling procedures and shipping instructions are specifically for systems using sample bottles provided by the Missouri Department of Health and Senior Services' State Public Health Laboratory. 

Sample Containers

These sample bottles contain a chlorine neutralizer either in liquid or crystalline form. They are sterile and ready for use when shipped. Do not rinse contents from the container.

Sample Collection

  1. Assemble all of the sampling supplies before you begin and wash your hands thoroughly before handling supplies.
  2. Go to the sampling location(s) specified in the system’s written bacteriological sample siting plan and sample collection schedule. Take the sample from a clean smooth-nosed cold-water tap if possible. Avoid drinking fountains, leaky faucets and frost-proof yard hydrants, since it is not practical to sterilize these fixtures.
  3. Remove any aerators, strainers, gaskets, or hoses because they may harbor bacteria. 
  4. Open the cold-water tap (or hot water if a mixing faucet is used) for approximately three minutes before collecting the sample. This should adequately clear the water line.
  5. Flame-sterilize or chemically disinfect the tap. Do not flame-sterilize if the tap is plastic or has aerators attached. Disinfect the tap by thoroughly rinsing both the inside and outside of the tap with a mixture of 50% department-approved sodium hypochlorite (bleach) and 50 percent tap water. Chemical disinfection alternatives of a sample tap include the use of ethyl alcohol greater than 60 percent or Isopropyl alcohol (rubbing alcohol) of greater than 70 percent by volume. Take extreme care with handling bleach or other strong oxidizing solutions. 
  6. Flush the tap for an additional three minutes with cold water and then reduce to a gentle flow to about the width of a pencil. Do not change the water flow once you have started filling the bottle. 
  7. Grasp the cap along the top edge and remove carefully. Do not touch the inside with your fingers. Hold the bottle in one hand and the cap in the other. Do not lay the cap down or put it in a pocket. Also, take care not to contaminate the sterile bottle or cap with your fingers or permit the faucet to touch the inside of the bottle. 
  8. Hold the bottle so that there is nothing obstructing the water flowing from the tap and entering the bottle.
  9. Fill bottle until the water sample level is between the two lines on the bottle (100 mL and 120 mL). From a side view, the water sample level in the center of the bottle must be above the 100 mL fill line and below the 120 mL line. If there is less than 100 mL of water in the bottle, samples are not tested. In addition, if the water level is above the 120 mL line, samples are not tested. If you overfill the bottle during this process, pour off any excess water to get the water sample level between the two lines.
  10. Place the cap on the bottle and twist it down firmly to prevent leakage during transit. 
  11. Complete the Environmental Sample Collection Form (sample form) with all the necessary collection information using waterproof ink. There must be one sample form for each sample bottle. Be certain the Sample Type, Sample Collection Point ID, Date, Time (using 24-hour clock), PWS Name and ID Number are correct and the Bottle Number on the sample form matches the number on the side of the bottle. Also, if your system is disinfected with chlorine or chloramines, provide the appropriate disinfectant residual(s) (Free Chlorine and/or Total Chlorine) on the sample form. If the sample collection point ID is different from what is on your sample siting plan or sample collection schedule, provide explanation for discrepancy on a sampling log.
  12. Make a copy of each completed sample form for recordkeeping (recommended).

Shipping Instructions

Place the completed sample form inside the box along with the corresponding sample bottle and seal the box with the mailing label provided.

  • If you use the Missouri Department of Health and Senior Services' Courier Services to deliver the sample(s), it is important to drop off the sample(s) by 10:30 a.m., the same day as collected, at any courier pickup location ​​to be certain the sample(s) reach the State Public Health Laboratory within 30 hours of collection, as required. The Department of Health and Senior Services also provides a printable Courier Drop off Locations and Times list.
  • If you choose to use the U.S. Postal Service to deliver the sample(s), remember the 30-hour time limit starts when the sample is collected. The Missouri Department of Natural Resources recommends you use Priority Mail or faster to mail water samples. Contact the Missouri Department of Natural Resources’ Public Drinking Water Branch for more information at 573-751-1077.

Sample Results

  • For systems using the State Public Health Laboratory, sample results are available within four to five days in Drinking Water Watch
  • For systems using an independent laboratory, contact the lab for sample results. Systems using independent laboratories are responsible for ensuring the sample results are submitted to the department by the 10th of the following month.

Sometimes despite taking all the precautions and following the sample collection procedures, you may receive notification that a routine sample is total-coliform positive. 

  • If using the State Public Health Laboratory, you would receive notification from the Missouri Department of Natural Resources regarding the coliform-positive routine. You will also be given specific instructions to collect a set of three repeat samples for each coliform-positive routine, according to your sample siting plan. Collect repeats from the original routine sample location, upstream and downstream locations within five service connections, or from approved alternative repeat sites, or approved locations specified in a standard operating procedure according to the sample siting plan. In addition to three repeat samples, groundwater systems with well(s) that are not provided 4-log virus inactivation and not conducting compliance monitoring under the Ground Water Rule are required to collect a source water sample at an approved location before treatment from each well in service at the time of collection of the coliform-positive routine sample. 
  • If using an independent lab for bacteriological analysis, the system is responsible for collecting all the necessary repeat samples and triggered source water samples, if required under the Ground Water Rule, within 24 hours of notification of the coliform-positive sample. Not all independent laboratories notify the department of a coliform-positive sample until the next month. 
  • If a system serving a population of 1,000 or less has two or more total coliform-positive samples in a monitoring period, or a system serving more than 1,000 has a number of positive samples exceeding 5% of compliance samples taken in a given monitoring period, or any system fails to collect all of the required repeat samples within 24 hours of notification or within a department specified timeframe, the system will exceed the treatment technique trigger (TTT).
    • The department will notify a system exceeding the TTT for the first time within the last 12 months and require the system to conduct a Level 1 Assessment. 
    • The department will notify a system exceeding the TTT for a second time or more within the last 12 months, or a system that exceeds the E. coli Maximum Contaminant Level that a Level 2 Assessment is required. The department’s Regional Office staff will conduct the Level 2 Assessment. 
    • The purpose of an assessment is to look for and identify any sanitary defects that may have caused the contamination and the system must take corrective action to any sanitary defects discovered within 30 days of triggering the assessment or within the department specified timeframe.


Chlorine Monitoring

Chlorine conversion in routine public drinking water system maintenance

For more information, contact your local department regional office.


General Information

For Public Water Systems

Community Water Systems: A public water system that supplies water to the same population year-round. 

Nontransient Noncommunity Water Supplies: A public water system that regularly supplies water to at least 25 of the same people at least six months per year. Some examples are schools, factories, office buildings and hospitals which have their own water systems.

Customer Notification of Lead and Copper Results

Documents Included in Sample Kit

Lead and Copper Information for New Water Systems

Lead Public Education Documents

Routine Lead and Copper Monitoring Documents

Forms and Other